Known power switching equipment utilizes a large number of parts some of which are disposed within large open enclosing structures and which may involve the use of several switch operating springs. Such devices are subject to contamination by moisture and by foreign particles from atmosphere and may become so encrusted with pollutants that operation of the relatively movable parts becomes impossible.
U.S. Pat. No. 3,190,983 is representative of a so-called snap-action type switch which includes a great number of parts and which is characterized by a high degree of complication. While a switch constructed according to U.S. Pat. No. 3,190,983 is capable of fast action, it is necessary to initiate an operation of the switch by some special means such as electromagnetic means or thermally responsive means. Of course such specialized actuating devices require substantial maintenance and are expensive as well as complicated when used as a part of a switch operating mechanism.